1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a dual screen liquid crystal display device having a color filter on TFT (COT) structure.
2. Description of the Related Art
Liquid crystal display (LCD) devices have advantages such as light weight, slim profile, and low power consumption, and are widely used for portable computers, office automation machines, and audio/video apparatuses. The LCD device includes two substrates and a liquid crystal layer interposed between the two substrates, and displays an image by manipulating transmission of light through the liquid crystal by displacing liquid crystal molecules using an electric field generated upon voltage application. Since the LCD device dose not generate light by itself, it uses ambient light or a backlight assembly as a light source.
Generally, LCD devices can be classified into two different categories: transmission type and reflection type, depending on how light is used. The transmission type LCD device is provided with a backlight assembly. When a voltage is applied to the transmission type LCD device, liquid crystal molecules are aligned to transmit or block light provided from the backlight assembly, thereby displaying an image. The reflection type LCD device is provided with a reflector. When a voltage is applied to the reflection type LCD device, liquid crystal molecules are aligned to transmit or block light, such as ambient light, that is incident from the exterior and then reflected by the reflector, thereby displaying an image.
A transflective type LCD device incorporating features of both the transmission type LCD device and the reflection type LCD device has been proposed. The transflective type LCD device uses the light provided by the backlight assembly or the ambient light. More particularly, the transflective LCD device uses the light provided by the backlight assembly in the transmission mode, and uses the ambient light in the reflection mode. In the transmission mode, an image is displayed using light provided by the backlight assembly disposed at a rear side of the LCD device that transmits straight through the liquid crystal panel. In the reflection mode, an image is displayed using light incident from a front side of the liquid crystal panel that is reflected by the reflector disposed at a rear side of the liquid crystal panel. Accordingly, the transflective LCD device always displays an image only at a front surface thereof.
Recently, a dual screen LCD device that can display an image at a front surface and at a rear surface has been investigated. Since the dual screen LCD device can be applied to a mobile phone, a waiting room television or the like, enormous ripple effect is anticipated. However, research and productization for a dual screen LCD device is not yet sufficient.